Cooling fan clutch

ABSTRACT

A disk-shaped cover has a first toothed portion at one surface thereof. A housing is coupled with the cover such that a space is defined therebetween. The housing has a second toothed portion at one surface thereof, facing the first toothed portion. A shaft is rotatably disposed through a middle portion of the housing. A fan is fixedly connected to the housing and rotatable with the housing. A rotor is mounted in the space between the cover and the housing, engaged with and rotatable with the shaft, with third and fourth toothed portions at both surfaces thereof, engaged with the first and second toothed portions, respectively. An operation unit controls an amount of fluid supplied to the space between the cover and the housing to control a frictional force generated between the rotor, the housing, and the cover. A control unit controls the operation unit based on a coolant temperature.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to, and the benefit of, Korean Patent Application No. 10-2007-0130422, filed in the Korean Intellectual Property Office on Dec. 13, 2007, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a clutch that controls a cooling fan, such as those used in automobile radiators to maintain a constant coolant temperature.

(b) Description of the Related Art

Generally, a cooling fan cools engine coolant that passes through the radiator. The cooling fan rotates quickly, and lowers the temperature of the coolant quickly, if the temperature of the coolant is higher than or equal to a specific temperature. The cooling fan rotates slowly, and lowers the temperature of the coolant slowly, if the temperature of the coolant is lower than the specific temperature. Operation of the cooling fan is controlled by a cooling fan clutch.

A rotor is mounted between a cover and a housing, and the fan is mounted on the housing. Silicon oil is stored in an oil storage area between the cover and the housing, and is supplied by opening or closing the oil storage area. Opening or closing of the oil storage area is controlled by a bimetal valve on the cooling fan clutch, which expands or contracts with temperature of air passing through the radiator to open and close the oil storage area. The silicon oil is supplied, controlling the frictional force between the housing and the rotor to control the speed of the cooling fan.

The bimetal valve expands or contracts by the temperature of the air, not the coolant, which provides less than ideal responsiveness to coolant temperature. The temperature of the coolant may thus quickly rise and the engine may overheat during high-speed travel. In addition, since the fan clutch maintains its operation state for a very long time, fuel mileage may be reduced. Further, since operation time of the cooling fan becomes longer, there may be unnecessary noise.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

A disk-shaped cover has a first toothed portion at a radially outward portion of one side surface thereof. A housing is coupled with the cover such that a space is defined therebetween. The housing has a second toothed portion at a radially outward portion of one side surface thereof, facing the first toothed portion. A shaft is rotatably disposed through a middle portion of the housing. A fan is fixedly connected to the housing and rotatable with the housing. A rotor is mounted in the space between the cover and the housing, engaged with and rotatable with the shaft, with third and fourth toothed portions at radially outward portions of both side surfaces thereof, engaged with the first and second toothed portions, respectively. An operation unit controls an amount of fluid supplied to the space between the cover and the housing to control a frictional force generated between the rotor, the housing, and the cover. A control unit controls the operation unit based on a coolant temperature.

A bearing may be interposed between the shaft and the housing such that the housing can rotate relative to the shaft.

The operation unit may include: a fluid storage area in a portion of the space between the cover and the housing, for storing the fluid; a screen for fluidly isolating the fluid storage area, with a passage through which the fluid in the fluid storage area can be supplied to another portion of the space between the cover and the housing; and a valve for closing and opening the passage by control of the control unit.

The operation unit may also include: an electromagnet for receiving current and generating a magnetic force by the control of the control unit; a plate configured to be moved by the magnetic force of the electromagnet; and a valve rod connected to the plate and the valve, and moving the valve according to motion of the plate.

The plate and the electromagnet may be exterior to the housing, and the valve rod may penetrate the housing.

A bearing may be interposed between the shaft and the electromagnet. The control unit may open the valve and supply the fluid to the other portion of the space between the cover and the housing if the coolant temperature is higher than or equal to a predetermined temperature.

A coolant temperature sensor may be provided for detecting the coolant temperature and transmitting a signal corresponding thereto to the control unit.

The fluid may be silicon oil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly schematic cross-sectional view of a cooling fan clutch according to an exemplary embodiment of the present invention.

FIG. 2 is an enlarged view of an operation unit shown in FIG. 1.

FIG. 3 is a flowchart showing operation of a cooling fan clutch according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a cooling fan clutch according to an exemplary embodiment of the present invention includes a cover 10, a housing 12, a fan 20, a rotor 14, an operation unit 34, an engine control unit 100, and a coolant temperature sensor 130.

The cover 10 has a disk shape and is provided with a first toothed portion 40 at a radially outward portion of one side surface thereof.

The housing 12 has an interior surface 36 at a middle portion thereof, and is coupled with the cover 10 such that a space is formed therebetween. A shaft 16 is rotatably disposed in the interior surface 36, and a second toothed portion 42 is provided at a radially outward portion of one side surface of the housing 12, opposite the first toothed portion 40. A bearing 18 is interposed between the housing 12 and the shaft 16, and reduces frictional force therebetween that is generated by relative rotation thereof.

The fan 20 is fixedly connected to the housing 12, and rotates together with the housing 12 so as to cool a coolant.

The rotor 14 is rotatably mounted in the space between the cover 10 and the housing 12, and a middle portion of the rotor 14 is splined to the shaft 16 so as to rotate together with the shaft 16. Third and fourth toothed portions 38 are provided at both side surfaces (left and right surfaces in FIG. 1) of radially outward portions of the rotor 14, to intermesh with the first and second toothed portions 40 and 42, respectively. When the rotor 14 rotates, the housing 12 and the cover 10 also rotate by frictional force between the first, second, and third toothed portions 40, 42, and 38.

The operation unit 34 controls the amount of silicon oil supplied to the space between the cover 10 and the housing 12, and particularly to the toothed portions 40, 42, and 38. If a lot of silicon oil is supplied, the frictional force between the rotor 14 and the housing 12, and between the rotor 14 and the cover 10, is large, and rotation speed of the fan 20 is high. If a small amount of silicon oil is supplied, the frictional force between the rotor 14 and the housing 12, and between the rotor 14 and the cover 10, is small, and the rotation speed of the fan 20 is low.

The coolant temperature sensor 130 detects the coolant temperature and transmits a signal corresponding thereto to the engine control unit 100. The engine control unit 100 controls operation of the operation unit 34 based on the coolant temperature. For example, the engine control unit 100 turns an operation switch 110 on or off according to the coolant temperature, and accordingly current is applied to the operation unit or not.

In addition, the cooling fan clutch includes a power source 140 and an ignition switch 120. If the ignition switch 120 is turned on, the power source 140 is electrically connected to the operation switch 110, but if the ignition switch 120 is turned off, the electrical connection between the power source 140 and the operation switch 110 is cut off.

Referring to FIG. 2, the operation unit 34 includes an oil storage area 22, a screen 24, a valve 30, an electromagnet 26, a metal plate 32, and a valve rod 28.

The oil storage area 22 is disposed in the space between the cover 10 and the housing 12, and the silicon oil is stored in the oil storage area 22.

The screen 24 closes off one surface of the oil storage area 22, and is provided with an oil passage 44 through which the silicon oil can be supplied from the oil storage area 22 to the space between the cover 10 and the housing 12. The valve 30 selectively opens and closes the oil passage 44.

The electromagnet 26 receives a current from the power source 140 and generates a magnetic force when the engine control unit 100 turns on the operation switch 110.

The metal plate 32 is mounted near the electromagnet 26, and moves left and right in FIG. 2 by the magnetic force of the electromagnet 26. That is, if the electromagnet 26 generates the magnetic force, the metal plate 32 moves night.

The valve rod 28 is fixedly connected to the valve 30 and the metal plate 32. When the metal plate 32 moves to the right, the valve rod 28 moves the valve 30 to the right, closing the oil passage 44. When the electromagnet 26 does not generate the magnetic force and the metal plate 32 is not pulled to the right, the valve 30 moves left by pressure of the silicon oil, opening the oil passage 44.

The metal plate 32 and the electromagnet 26 are mounted at an exterior of the housing 12. This arrangement prevents the magnetic force from being affected by the silicon oil.

In addition, a bearing 18 is interposed between the electromagnet 26 and the shaft 16 such that the electromagnet 26 is always stationary, regardless of the rotation of the shaft 16.

The silicon oil in the space between the cover 10 and the housing 12 can be returned into the oil storage area 22 in ways that will be apparent to people of ordinary skill in the art based on the teachings herein.

Referring to FIG. 3, in operation, the engine control unit 100 determines whether the ignition switch 120 is turned on at step S210.

If the ignition switch 120 is turned on, the engine control unit 100 determines whether the coolant temperature is higher than or equal to a predetermined temperature at step S220.

If the coolant temperature is lower than the predetermined temperature, the engine control unit 100 turns on the operation switch 110 and the current is applied to the operation unit 34 at step S240. In this case, the electromagnet 26 generates the magnetic force, the metal plate 32 moves to the right in the drawings, and the valve 30 closes the oil passage 44. Therefore, the friction force between the rotor 14 and the housing 12 is small and the rotation of the fan 20 slows down.

If the coolant temperature is higher than or equal to the predetermined temperature, the engine control unit 100 turns off the operation switch 110 and cuts off current supply to the operation unit 34 at step S230. In this case, the electromagnet 26 does not generate a magnetic force, the valve 30 moves to the left in the drawings by the pressure of the silicon oil, and the valve 30 opens the oil passage 44. Therefore, the silicon oil is supplied between the rotor 14 and the housing 12 and the friction force between the rotor 14 and the housing 12 is large. Therefore, the rotation of the fan 20 speeds ups.

Steps S220-S240 repeat until the ignition switch is turned off

Because the operation unit is controlled based on coolant temperature, and because the electromagnet generates the magnetic force according to the applied current, operational responsiveness to the coolant temperature is improved over the prior art, improving cooling performance. Therefore, damage to the engine is prevented.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

1. An apparatus, comprising: a cover with a disk shape, comprising a first toothed portion at a radially outward portion of one side surface thereof; a housing coupled with the cover such that a space is defined therebetween, the housing comprising a second toothed portion at a radially outward portion of one side surface thereof facing the first toothed portion; a shaft, rotatably disposed through a middle portion of the housing; a fan fixedly connected to the housing and rotatable with the housing; a rotor mounted in the space between the cover and the housing, engaged with and rotatable with the shaft, comprising third and fourth toothed portions at radially outward portions of both side surfaces thereof engaged with the first and second toothed portions, respectively; an operation unit for controlling an amount of fluid supplied to the space between the cover and the housing so as to control a frictional force generated between the rotor, the housing, and the cover; and a control unit for controlling the operation unit based on a coolant temperature.
 2. The apparatus of claim 1, further comprising a bearing interposed between the shaft and the housing such that the housing can rotate relative to the shaft.
 3. The apparatus of claim 1, wherein the operation unit comprises: a fluid storage area disposed in a portion of the space between the cover and the housing, for storing the fluid; a screen for fluidly isolating the fluid storage area, and comprising a passage through which the fluid in the fluid storage area can be supplied to another portion of the space between the cover and the housing; and a valve for closing and opening the passage by control of the control unit.
 4. The apparatus of claim 3, wherein the operation unit further comprises: an electromagnet for receiving current and generating a magnetic force by the control of the control unit; a plate configured to be moved by the magnetic force of the electromagnet; and a valve rod connected to the plate and the valve, and moving the valve according to motion of the plate.
 5. The apparatus of claim 4, wherein the plate and the electromagnet are exterior to the housing, and the valve rod penetrates the housing.
 6. The apparatus of claim 5, further comprising a bearing interposed between the shaft and the electromagnet.
 7. The apparatus of claim 4, wherein the control unit is configured to open the valve and supply the fluid to the other portion of the space between the cover and the housing if the coolant temperature is higher than or equal to a predetermined temperature.
 8. The apparatus of claim 1, further comprising a coolant temperature sensor for detecting the coolant temperature and transmitting a signal corresponding thereto to the control unit.
 9. The apparatus of claim 1, wherein the fluid comprises silicon oil. 